public void CompositeMetricExporter_Works_If_Both_Exporters_Defined()
        {
            // arrange
            var firstExporter = new Mock<IMetricExporter>();
            var secondExporter = new Mock<IMetricExporter>();

            // act
            using var result = new CompositeMetricExporter(firstExporter.Object, secondExporter.Object);
            result.Start();

            // assert
            firstExporter.Verify(me => me.Start(), Times.Once);
            secondExporter.Verify(me => me.Start(), Times.Once);
        }
        public void CompositeMetricExporter_Works_If_One_Exporter_Null()
        {
            // arrange
            var metricExporter = new Mock<IMetricExporter>();

            // act
            using var first = new CompositeMetricExporter(null, metricExporter.Object);
            using var second = new CompositeMetricExporter(metricExporter.Object, null);
            first.Start();
            second.Start();

            // assert
            metricExporter.Verify(me => me.Start(), Times.Exactly(2));
        }